dass-Clauses and Complement Clauses

A complement clause is a whole clause doing the work of an object. When you say I know that you're right or I believe that he'll come, the bold part is not a noun but an entire clause functioning as the object of know or believe. In German this is the dass-clause, and like every German subordinate clause it has two non-negotiable features: a comma before dass and the finite verb at the very end. This page covers the dass-clause, its yes/no-question cousin the ob-clause, the colloquial dass-less variant that keeps main-clause word order, and the spelling trap that dass (the conjunction) and das (the article/pronoun) are different words.

What a dass-clause does

A dass-clause is the spelled-out content of a verb of saying, thinking, knowing, feeling, or perceiving. It answers "what?" — I know *what? → that you're coming.* The whole clause is the object.

In every case the main clause is short — Ich glaube, Ich weiß, Sie hat gesagt — and the dass-clause delivers the content. English very often drops "that" (I think he's right), but the German dass behaves more like a structural switch than an optional word, and dropping it has consequences for word order, as we will see.

Verb-final and the comma

Two rules apply the instant dass appears. First, a comma goes before dass — always, no exceptions. Second, the finite verb moves to the end of the dass-clause, because dass is a subordinating conjunction and German sends the conjugated verb to the back of every subordinate clause.

Watch the verb. In ordinary main-clause order this would be dieser Film ist viel zu lang (verb second). Inside the dass-clause it becomes dieser Film viel zu lang ist — the verb travels all the way to the end. With a compound tense, the auxiliary takes the final slot and the participle sits immediately in front of it: gekommen bist. This is the single most important thing to get right about dass-clauses, and it is the rule English speakers most often break, because English keeps ordinary word order after "that."

dass vs das — one s or two

This pair is the most notorious spelling minefield in German, and it is genuinely a spelling distinction: das and dass are pronounced identically. They are nonetheless different words.

• das (one s) — the neuter article (das Buch), the demonstrative (das ist schön), or the relative pronoun (das Buch, das ich lese).
• dass (two s) — the subordinating conjunction "that," introducing a complement clause.

The reliable test: replace the word with dieses, jenes, welches. If one of those fits, you need das (one s); it is an article, demonstrative, or relative pronoun. If none fits and the word is just gluing a content clause onto a verb of saying/thinking, you need dass (two s). In Ich glaube, dass er kommt, you cannot say Ich glaube, welches er kommt — so it is dass. In das Buch, das ich lese, you can say das Buch, welches ich lese — so it is das.

ob-clauses: the yes/no version

When the embedded content is a yes/no question ("whether / if …"), German does not use dass. It uses ob. The construction is otherwise identical: comma before ob, verb at the end.

The split is clean: a statement turns into a dass-clause (Ich weiß, dass er kommt — "I know that he's coming"), a yes/no question turns into an ob-clause (Ich weiß nicht, ob er kommt — "I don't know whether he's coming"). English uses "whether/if" here, and the German ob never alternates with dass. (Embedded w-questions use the question word itself — ich weiß nicht, wann er kommt — covered on the indirect-questions page.)

The dass-less variant: V2 in casual speech

After a small group of high-frequency verbs of saying and believing — glauben, denken, meinen, sagen, hoffen, finden — German colloquially drops dass and keeps the embedded clause in ordinary main-clause (V2) word order, with the verb in second position. This is the spoken-German default after these verbs.

This is the one place where leaving out the linking word changes the grammar. With dass, the verb goes to the end (Ich glaube, dass er recht hat); without dass, the verb stays in second position (Ich glaube, er hat recht). You may not mix them — Ich glaube, dass er hat recht is wrong because it keeps V2 order while dass is present. Either keep dass and send the verb to the end, or drop dass and keep V2. The dass-less form is informal and very common in speech; in formal writing the full dass-clause is preferred.

English contrast

English and German agree that "that" can often be omitted (I think he's right ≈ Ich glaube, er hat recht). The crucial difference is what omission costs. In English, dropping "that" changes nothing about word order. In German, the presence or absence of dass dictates word order: dass forces verb-final, its absence permits V2. English speakers therefore tend to keep V2 even after dass (because that is normal in English), producing the classic error dass er hat recht. The other contrast is the spelling burden: English has no das/dass homophone problem, so the choice never crosses an English speaker's mind until German forces it on them.

Common Mistakes

Key Takeaways

• A dass-clause is a complement clause acting as the object of a verb of saying, thinking, or feeling.
• dass forces a comma before it and the finite verb to the end.
• An embedded yes/no question uses ob, never dass (Ich weiß nicht, ob…).
• dass (two s) = the conjunction; das (one s) = article, demonstrative, or relative pronoun. Test by substituting dieses/welches.
• After glauben, denken, meinen, sagen in speech, German often drops dass and keeps V2 (Ich glaube, er hat recht) — but you can never have dass and V2 together.